Lancets are conventionally used to puncture skin for providing blood samples. They are used primarily by people suffering from diabetes since they need to regularly analyse their blood sugar content. Lancets conventionally include a puncturing device, in the form of a small blade or a needle, that is advantageously mounted to a body.
Most lancets include a housing and a mechanism so configured as to retract the body in the housing when the lancet is not in use. This feature is advantageous since it prevents accidental use of the lancet.
A distinction can be made between two types of lancets. The first type usually includes a pen like housing that allows the removal of both the body and the needle so as to replace them after use. The internal mechanism of such lancet must be configured to allow the body to safely retract in the pen like housing but also to allow the body to be removed therefrom after use, which increases the complexity of the internal mechanism.
The second type of lancets (hereinafter referred to as disposable lancets) are relatively simpler to manufacture even though they may be provided with a retractable mechanism.
An example of such disposable lancet is described in the U.S. Pat. No. 4,624,253, naming James A. Burns as the inventor and issued on Nov. 25, 1986. Burns discloses a lancet that includes a generally cylindrical housing provided with a handle portion, a puncturing device holder having a puncturing blade mounted thereto and a helicoidal compression spring. The puncturing device holder is so mounted in the housing as to be reciprocally movable therein while being biased towards a neutral position by the helicoidal spring.
A drawback of Burns' lancet is that the assembly of a spring around the puncturing device holder can be tedious thus increasing the costs involved in the manufacturing of such a lancet. Also, since the puncturing blade is not embedded in a cap before use, Burn's lancet requires additional packaging to insure that the blade remains sterilized.
Another disposable lancet is described in the U.S. Pat. No. 5,529,581, issued on Jun. 25, 1996 and naming Robert Cusack as the inventor. Cusack's lancet includes a spring member, in the form of a curved invertible structure, that biases a small puncturing blade towards a safe position when not in use. A drawback of Cusack's lancet is that the retractable mechanism does not allow the blade to be embedded in a cap thus requiring additional packaging to insure that the blade remains sterilized.